(navigation image)
Home American Libraries | Canadian Libraries | Universal Library | Community Texts | Project Gutenberg | Children's Library | Biodiversity Heritage Library | Additional Collections
Search: Advanced Search
Anonymous User (login or join us)
Upload
See other formats

Full text of "Text Book Of Mechanical Engineering"

68o                        Weight of Fly Wheel.

keeping the fluctuation of velocity within a certain percentage of
the mean. Let v  mean velocity, and let

Total fluctuation of velocity = -7 of v

Ri

then the value of k 'depends on the regularity required, and
may vary from 100 for very steady driving, to 20 where constant
speed is of little value. With feet and seconds units, let z^ be
maximum velocity and z>2 minimum velocity of the fly wheel at its
mean radius, consequent on absorbing and delivering the given
^energy, and let E represent the energy area, or the 49,560 foot
pounds of Fig. 662, while the velocity falls from v^ to v%.

j      z*> (V ~ z>22)
Energy delivered =  ^ - ^

2<r

where w is the weight of the fly wheel. But this energy is equal
to the area E,

I

NOW Vl - 7/2 = V   X  -                   flj + V2 = 2 V

27T RN

and     v =  - -
60

R being radius of gyration of fly wheel.
Putting also the fly-wheel weight in tons,

-        (#! + V%) (7^ - V^) 2240         2 V2 X 2 240

&32'2 ^ 60 x 60               E^

R2N2

Generally R may be taken at centre of * rim section, but if
great accuracy be required, assume a fly-wheel section, replac-
ing the arms by a thin disc of equal weight : then, moment of
inertia ,of volume (second moment) of a solid of revolution, or
JT= volume xR2, which is the third moment of the generating